A unique serine-rich repeat protein (Srr-2) and novel surface antigen (ε) associated with a virulent lineage of serotype III Streptococcus agalactiae

Seifert, Kyle; Adderson, Elisabeth E.; Whiting, April; Bohnsack, John F.; Crowley, Paula J.; Brady, L. Jeannine

doi:10.1099/mic.0.28516-0

Cited by 109 publications

(131 citation statements)

References 61 publications

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“…agalactiae possess Srr-2. They are highly virulent in an in vivo mouse model of neonatal sepsis in comparison with Srr-2-negative serotype III strains (Seifert et al, 2006), suggesting that Srr-2 likely contributes to bacterial pathogenesis. The function of the other serine-rich protein, Srr-1, has also been investigated.…”

Section: Serine-rich Glycoproteins Play Important Roles In Bacterial mentioning

confidence: 99%

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Glycosylation and biogenesis of a family of serine-rich bacterial adhesins

2009

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Glycosylation of bacterial proteins is an important process for bacterial physiology and pathophysiology. Both O-and N-linked glycan moieties have been identified in bacterial glycoproteins. The N-linked glycosylation pathways are well established in Gram-negative bacteria. However, the O-linked glycosylation pathways are not well defined due to the complex nature of known O-linked glycoproteins in bacteria. In this review, we examine a new family of serine-rich O-linked glycoproteins which are represented by fimbriae-associated adhesin Fap1 of Streptococcus parasanguinis and human platelet-binding protein GspB of Streptococcus gordonii. This family of glycoproteins is conserved in streptococcal and staphylococcal species. A gene cluster coding for glycosyltransferases and accessory Sec proteins has been implicated in the protein glycosylation. A two-step glycosylation model is proposed. Two glycosyltransferases interact with each other and catalyse the first step of the protein glycosylation in the cytoplasm; the cross-talk between glycosylation-associated proteins and accessory Sec components mediates the second step of the protein glycosylation, an emerging mechanism for bacterial Olinked protein glycosylation. Dissecting the molecular mechanism of this conserved biosynthetic pathway offers opportunities to develop new therapeutic strategies targeting this previously unrecognized pathway, as serine-rich glycoproteins have been shown to play a role in bacterial pathogenesis.

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Section: Serine-rich Glycoproteins Play Important Roles In Bacterial mentioning

confidence: 99%

“…Two serine-rich proteins, Srr-1 and Srr-2, have been described for Strep. agalactiae strains 2603V/R and J48 (Samen et al, 2007;Seifert et al, 2006). Serotype III delta/epsilon-positive strains of Strep.…”

Section: Serine-rich Glycoproteins Play Important Roles In Bacterial mentioning

confidence: 99%

Glycosylation and biogenesis of a family of serine-rich bacterial adhesins

2009

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“…Although identified only relatively recently, in part because of their extremely high apparent molecular mass and failure to react with conventional protein stains, these glycoproteins have been found not only to bind specific receptors on human tissues (7,35,45,47,48,57) but also to contribute to virulence, as measured by animal models of infection (32,40,42,46).…”

Section: Gspb Is a Cell Surface Glycoprotein Expressed By Streptococcmentioning

confidence: 99%

“…This unusual adhesin is a member of an expanding family of serine-rich glycoproteins which includes Fap1 of Streptococcus parasanguinis, Hsa of S. gordonii Challis, SraP of Staphylococcus aureus, the Srr proteins of Streptococcus agalactiae, and the SrpA proteins of Streptococcus sanguinis and Streptococcus cristatus (21,35,40,42,44,56). Although identified only relatively recently, in part because of their extremely high apparent molecular mass and failure to react with conventional protein stains, these glycoproteins have been found not only to bind specific receptors on human tissues (7,35,45,47,48,57) but also to contribute to virulence, as measured by animal models of infection (32,40,42,46).…”

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confidence: 99%

Glycine Residues in the Hydrophobic Core of the GspB Signal Sequence Route Export toward the Accessory Sec Pathway

2007

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The Streptococcus gordonii cell surface glycoprotein GspB mediates high-affinity binding to distinct sialylated carbohydrate structures on human platelets and salivary proteins. GspB is glycosylated in the cytoplasm of S. gordonii and is then transported to the cell surface via a dedicated transport system that includes the accessory Sec components SecA2 and SecY2. The means by which the GspB preprotein is selectively recognized by the accessory Sec system have not been characterized fully. GspB has a 90-residue amino-terminal signal sequence that displays a traditional tripartite structure, with an atypically long amino-terminal (N) region followed by hydrophobic (H) and cleavage regions. In this report, we investigate the relative importance of the N and H regions of the GspB signal peptide for trafficking of the preprotein. The results show that the extended N region does not prevent export by the canonical Sec system. Instead, three glycine residues in the H region not only are necessary for export via the accessory Sec pathway but also interfere with export via the canonical Sec route. Replacement of the H-region glycine residues with helix-promoting residues led to a decrease in the efficiency of SecA2-dependent transport of the preprotein and a simultaneous increase in SecA2-independent translocation. Thus, the hydrophobic core of the GspB signal sequence is responsible primarily for routing towards the accessory Sec system. GspB is a cell surface glycoprotein expressed by Streptococcus gordonii that mediates the high-affinity binding of this organism to human platelets (8). This unusual adhesin is a member of an expanding family of serine-rich glycoproteins which includes Fap1 of Streptococcus parasanguinis, Hsa of S. gordoniiChallis, SraP of Staphylococcus aureus, the Srr proteins of Streptococcus agalactiae, and the SrpA proteins of Streptococcus sanguinis and Streptococcus cristatus (21,35,40,42,44,56). Although identified only relatively recently, in part because of their extremely high apparent molecular mass and failure to react with conventional protein stains, these glycoproteins have been found not only to bind specific receptors on human tissues (7,35,45,47,48,57) but also to contribute to virulence, as measured by animal models of infection (32,40,42,46).Little is known thus far regarding the role of the carbohydrate residues on these glycoproteins. Our studies with GspB have indicated that the carbohydrate moieties are essential for maintaining the stability and solubility of this adhesin (9, 49). Two serine-rich regions of GspB (SRR1 and SRR2) (Fig.

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“…Both organization and number of annotated glycosyltransferases vary even within the same bacterial species such as S. agalactiae (Seifert et al 2006). SRRPs and protein glycosylation have been implicated in bacterial pathogenesis (Zhou and Wu 2009;Lizcano et al 2012), and it is tempting to hypothesize that the diversity of GTs in various bacterial species and strains may allow the bacteria to make differentially modified adhesion molecules tailored to their unique host environments.…”

Section: Glycosyltransferases Important For the Glycosylation Of Srrpsmentioning

confidence: 99%

Glycosyltransferase-mediated Sweet Modification in Oral Streptococci

Zhu

Zhang

2015

J Dent Res

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Bacterial glycosyltransferases play important roles in bacterial fitness and virulence. Oral streptococci have evolved diverse strategies to survive and thrive in the carbohydrate-rich oral cavity. In this review, we discuss 2 important biological processes mediated by 2 distinct groups of glycosyltransferases in oral streptococci that are important for bacterial colonization and virulence. The first process is the glycosylation of highly conserved serine-rich repeat adhesins by a series of glycosyltransferases. Using Streptococcus parasanguinis as a model, we highlight new features of several glycosyltransferases that sequentially modify the serine-rich glycoprotein Fap1. Distinct features of a novel glycosyltransferase fold from a domain of unknown function 1792 are contrasted with common properties of canonical glycosyltransferases. The second biological process we cover is involved in building sticky glucan matrix to establish cariogenic biofilms by an important opportunistic pathogen Streptococcus mutans through the action of a family of 3 glucosyltransferases. We focus on discussing the structural feature of this family as a glycoside hydrolase family of enzymes. While the 2 processes are distinct, they all produce carbohydrate-coated biomolecules, which enable bacteria to stick better in the complex oral microbiome. Understanding the making of the sweet modification presents a unique opportunity to develop novel antiadhesion and antibiofilm strategies to fight infections by oral streptococci and beyond.

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A unique serine-rich repeat protein (Srr-2) and novel surface antigen (ε) associated with a virulent lineage of serotype III Streptococcus agalactiae

Cited by 109 publications

References 61 publications

Glycosylation and biogenesis of a family of serine-rich bacterial adhesins

Glycosylation and biogenesis of a family of serine-rich bacterial adhesins

Glycine Residues in the Hydrophobic Core of the GspB Signal Sequence Route Export toward the Accessory Sec Pathway

Glycosyltransferase-mediated Sweet Modification in Oral Streptococci

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